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XJ Cherokee Conversion to WJ Front Brakes & Steering

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By: Michael J. Rollins - 5/2003

XJ Cherokee Conversion to WJ Front Brakes & Steering
Part 3 - Knuckles, Steering & Brakes

Introduction | Part 1 Booster/Master Cylinder | Part 2 Proportioning Valve | Part 3 Knuckles/Steering/Brakes

This is the third article in a series describing the addition of year 2000 WJ Grand Cherokee steering and brake components to my 1988 XJ Cherokee. In this part, I describe the conversion to TJ hubs and WJ knuckles, steering & brakes.



The 2wd front axle jig used to measure differences in parts from various Jeep models and to modify/prototype the parts needed to install it on my '88 XJ. 88 XJ Stuff at the top (knuckles and hub). Measuring tools in the middle. '00 WJ stuff at the bottom (knuckles and hub).
2wd axle jig. Old and new knuckles and hubs compared.

Axle Prototyping Stand

I started this project using a 2wd beam axle that I had welded a stand onto so I could measure the differences between YJ/TJ/XJ/ZJ/WJ parts, prototype the parts necessary to make it work, and then fit them on an axle without tearing down my front end until I was ready to install them. During this process I decided to use '00-'01 TJ/XJ hubs as they allowed me to use a .230" spacer which will re-center the axle shaft U joint between the ball joints on the WJ knuckles and allow the WJ brake rotor to center within the calipers. While spacing the hubs out I discovered that to properly support the hub in the knuckle required custom modifications and parts. I had to modify the hubs and find suitable aftermarket brake rotors. There are several ways to do this but I can only tell you what I did to deal with this problem.

Single piston '88 XJ brakes. Single piston '88 XJ brakes. Single piston '88 XJ brakes.
Dual piston '03 WJ brakes. Dual piston '03 WJ brakes. Dual piston '03 WJ brakes.
Comparing the old '88 brakes (top) to the new '03 brakes (bottom).

Hubs

First I had the '01 TJ hubs pressed apart and machined down so they were uniform across the whole area where it goes into the knuckle. The hubs were then pressed back together.

A custom machined '01 TJ hub next to a stock '00 WJ hub. A custom machined '01 TJ hub next to a stock '00 WJ hub. My custom machined hub spacer/adapters.
A custom machined '01 TJ hub next to a stock '00 WJ hub, and the spacer/adapters.

I then had custom hub spacer/adapters machined to space the hub out .230" (for axle U joint to ball joint alignment), and to support the hub within the knuckle even more so than the factory did. With this part now done I needed to find suitable aftermarket brake rotors.

The custom machined hub spacer/adapter on the custom machined '01 TJ hub. The custom machined hub spacer/adapter on the custom machined '01 TJ hub. The custom machined hub spacer/adapter on the custom machined '01 TJ hub.
The custom machined hub spacer/adapter on the custom machined '01 TJ hub.

Rotors

I did not like the factory WJ rotors due to a cast in depression area inboard of the stud holes. If I re-drilled these rotors to 5 on 4.5" the new holes would be too close to this area. This can be seen in the photo showing a rusty re-drilled stock one next to the aftermarket one I chose to use. I only found one aftermarket brake rotor that was machined smooth through this whole area. It was the Aimco SuperPremium 5118. I made a re-drilling jig that bolts on to drill the 5 on 4.5" bolt pattern into these new rotors. I drilled them on a drill press.

Custom machined hub/spacer/adapter on the '00 WJ knuckle. Stock 11" XJ rotor next to the 12" WJ rotor already drilled for 5x4.5" bolt pattern. Factory WJ rotor next to a aftermarket WJ rotor both are already drilled for 5x4.5" bolt pattern.
Custom machined hub/spacer/adapter on the '00 WJ knuckle. Stock 11" rotor (black) and factory WJ rotor (rusty) compared to the already-drilled aftermarket WJ rotor.

Calipers

I chose to use the newer '03 WJ calipers but could have used the 99-02 ones. Both are 48mm dual piston calipers and mount to the knuckle the same way but the newer ones have a few improvements. The newer ones have a better slide setup, metal pistons, and the brake pads are narrower/longer. This reduces the rotor warping problems that the earlier calipers/pads may have caused. These brakes are meant to be used with 16" wheels but I didn't want to change my 15x8" TJ Canyon wheels. I am using 1.25" wheel spacers so that I have 4" backspacing which I feel is best for the 7" of lift I have on my XJ. I recommend switching to 16" wheels rather than dealing with the caliper clearance issues which may be more severe on other setups but I did make them work for my setup. The earlier calipers would have fit with less grinding to make my rims to fit but I wanted to use the newer ones. There is a picture at the end showing the older style caliper.

An '88 XJ single piston caliper next to the '03 WJ dual piston caliper. Both '03 WJ calipers. Note the grinding marks on one for wheel clearance. Both '03 WJ calipers. Note the grinding marks on one for wheel clearance.
An '88 XJ single piston caliper next to the '03 WJ dual piston caliper. Both 03 WJ calipers compared. Note the grinding marks on one for wheel clearance.

I assembled the custom machined spacer/adapters, custom machined hubs, aftermarket rotors that were re-drilled to the 5 on 4.5" bolt pattern, and the new calipers on my test axle stand. With this stuff assembled I then test fit my wheels and determined where and how much to grind off the calipers so the wheels would clear them. I used a 4" grinder to do all the major grinding and followed it up with a belt sander to smooth it all out. I then painted them with some matching silver paint. I have about 1/8" clearance to the rim which is just fine. After the grinding was done to the new caliper I noticed how the shape was more like the older style caliper but it would be a lot easier to just go to 16" wheels. Now that I was done it was time to dive in and tear down my front end knowing that there would still be some problems to deal with.

Removing all my old '88 XJ stuff. '00 WJ knuckles installed and measuring for the steering links to be made. Starting to assemble the WJ stuff on my '88 XJ.
Removing the old '88 XJ stuff and starting to assemble the WJ components. Center image shows measuring for the steering.

Assembly

I supported my front axle on jack stands and removed the wheels, wheel spacers, brake rotors, brake calipers (I left them hanging until I was ready to connect the hoses to the new ones), hubs, axle shafts, knuckles, and steering links. I painted the hubs, spacer/adapters, and knuckles black. I installed the '00 WJ knuckles (I recommend you check or change your ball joints before you do this), reinstalled my axle shafts, installed the hub spacer/adapters using anti-seize on all mating surfaces, installed the '01 TJ custom machined hubs also using anti-seize, torqued the hub bolts to 75ft lbs, torqued the axle nuts to 175ft lbs, installed the re-drilled 5 on 4.5" aftermarket rotors, and installed the custom ground '03 WJ loaded calipers. Now I disconnected the brake hoses from the old calipers and installed them on the new ones. Be careful to make sure the brake hoses have clearance between the tires and suspension parts on turns or during suspension travel. Once this was done I flushed and bled the brake system.

Both custom machined '01 TJ hubs ready to go on. '00 WJ knuckle and my front axle shaft installed. Custom machined hub spacer/adapter installed.
Custom machined '01 TJ hubs ready to go on. The '00 WJ knuckles and axle shaft, then the spacer/adapter installed

Steering

I was going to use the stock WJ steering links but due to limited time and not being able to get them quickly I had custom chromoly links made with heim joints. I also moved the steering links on top of the knuckles for better clearance and angle on the drag link. I reamed the holes in the knuckle out to 5/8" and I will be using grade 8 bolts with crimped lock nuts (not nylocks). The bolts have long shoulders and I cut off the excess thread for clearance. On the drag link I am also using anti separation washers for the heim joints. The tie rod heim joints are standard 3/4-16 right and left hand threaded with a custom sleeve pressed in the bolt hole to make a 5/8" bolt fit correctly. The drag link uses high misalignment right and left hand threaded 3/4-16 heim joints that already are setup for 5/8" bolts. The links are made out of 1.25" dia 1/8" wall chromoly tubing which has another piece of smaller 1/8" wall chromoly tubing inside making it 1/4" wall in total. To this I had right and left hand threaded 3/4-16 chromoly billet bungs which are TIG welded on.

Custom machined '01 TJ hub installed. Custom machined '01 TJ hub installed. Top view showing the hub, spacer, and knuckle. Custom ground for clearance '03 WJ caliper installed.
Custom machined '01 TJ hub installed. Top view showing the hub, spacer, and knuckle. '03 WJ caliper installed.

When I put the new steering links on I ran into a problem. The tie rod hit the factory track bar mount, the left spring mount, and sway bar links on turns. I knew I would have to redo the track bar anyway for proper angles although I was hoping to not have to for the short term but now I had to.

I started by grinding the sway bar mount welds and removing them (I still need to make some new ones later but for now I don't have them on).

A left side view from under the Jeep. A view from the wheel of the Jeep.
A left side view from under the Jeep. A view from the wheel of the Jeep.

Next I had to cut out almost the whole factory track bar bracket and some of the spring pad mounts underneath. I am using a modified Skyjacker bar currently but will make a new setup later that is better suited for this modification. I had some plate TIG welded in to reinforce the original steering dampener mount which is where the Skyjacker track bar mounts to the axle. This is normally weak and not suited for a track bar. On turns the tie rod now fits nicely under the new track bar mount although close. I plan on adding a steering dampener later like the setup on a WJ but for now it is working fine without one. Now that all this steering clearance and track bar stuff is done I can bolt everything up and take it out for a drive.

Right side linkage. Complete linkage. Note track bar is temporary till I can make a better setup. Left side linkage.
Right side, overall, and left side linkage views. Note track bar is temporary until I can make a better setup.

The steering is very tight and sensitive now but the biggest total improvement is the brakes. I expected an improvement in braking but didn't think they would work so well. In summary to say that they work better than when the vehicle was stock is an understatement. I am impressed with the improvements to my steering and brakes. I consider this a very important and worthwhile modification.

A right side view from under the Jeep. '99-'02 WJ dual piston caliper. 99-02 WJ dual piston caliper.
A right side view from under the Jeep. The '99-'02 WJ dual piston caliper (not used) is shown for comparison to the newer '03 version.

Introduction | Part 1 Booster/Master Cylinder | Part 2 Proportioning Valve | Part 3 Knuckles/Steering/Brakes





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